1. Field of the Invention
The present invention relates to a quick coupler which is used for connecting or disconnecting a halfway portion of a pressure line such as a hydraulic oil line.
2. Explanation of the Related Art
There is a conventional example of the quick coupler of this kind disclosed in Japanese Patent Publication No. 3-47975.
The conventional technique inserts rod-like closure members into a socket and a plug, respectively. And check members are provided in series with the respective closure members. A disk-like filter made of a sintered metal is arranged on an outer periphery of each of the closure members. Pressurized oil or the like fluid is made to pass axially of the disk-like filter.
According to the conventional technique, it is required to reduce a diameter of the disk-like filter so as to make the quick coupler compact. This entails a problem that the disk-like filter decreases its filtering area to result in enlarging a flow resistance of the fluid. In order to solve the problem, it may be sufficient to increase a filtration grading of the disk-like filter. However, in this case, there is a likelihood that large foreign matters which have passed through the disk-like filter might damage a checking performance of the check member.
Further, the conventional technique had another problem that when butting the two closure members against each other to forcedly open the check members, it required a large operational force for butting them.
The present invention has an object to provide a quick coupler which has a small flow resistance and a good checking performance. Further, the present invention has another object making it possible to decrease the operational force required when butting the two closure members against each other.
In order to accomplish the above object, the present invention has constructed a quick coupler in the following manner.
A first coupling includes a first flow passage and a second coupling includes a second flow passage. Rod-like closure members are inserted into the first flow passage and the second flow passage, respectively. A check member is provided in series with the closure member in at least one of the first flow passage and the second flow passage. The at least one of the flow passages has a halfway portion where a cylindrical filter is attached in an annular space defined on an outer periphery of the closure member. The cylindrical filter comprises an inner perforated sheet, a screen and an outer perforated sheet arranged in the mentioned order from an interior area.
The present invention offers the following advantage.
The cylindrical filter is arranged in the annular space defined on the outer periphery of the closure member. Therefore, pressurized oil or the like fluid passes through the screen of the cylindrical filter radially, thereby enabling the screen to secure a large filtering area. This makes it possible to reduce the flow resistance of the fluid which passes through the screen and at the same time to decrease the filtration grading of the screen. In consequence, large foreign matters are inhibited from passing through the screen to result in being able to keep the checking performance of the check member in a good condition.
The above construction could provide a quick coupler which has a small flow resistance and a good checking performance. In addition, the perforated sheets are arranged on both an inner side and an outer side of the screen. Owing to this arrangement, the quick coupler can attend-to two way flows each of which is caused in a case where pressurized fluid flows from an inner side of the cylindrical filter to an outer side thereof (an internal pressure acts on the filter) or in another case where pressurized fluid flows from the outer side of the cylindrical filter to the inner side thereof (an external pressure acts on the filter).
The present invention includes the following quick coupler.
Another cylindrical filter is attached at a halfway portion of the at least one of the flow passages and in an annular space defined on an outer periphery of the check member. The cylindrical filter comprises the inner perforated sheet, the screen and the outer perforated sheet arranged in the mentioned order from the interior area. In this case, it is possible to arrange on both of an inlet side and an outlet side of the check member, the cylindrical filters according to the present invention. This can keep the checking performance of the check member in a better condition.
The present invention further includes the following quick coupler.
The inner perforated sheet, the screen and the outer perforated sheet are overlaid or laminated one on another in the mentioned order from the interior area to thereby form a pipe-like overlaid body. The overlaid body has its opposite ends fixed by ring members each of which is U-shaped when seen in section. In this case, the cylindrical filter can be readily manufactured.
Moreover, in order to accomplish the another object, the present invention has constructed a quick coupler in the following manner.
Two closure members are arranged within a first housing of a first coupling and within a second housing of a second coupling, respectively, so that they can butt against each other. A check member is provided in at least one of the first housing and the second housing. The check member comprises a member of a larger diameter and a member of a smaller diameter. The larger-diameter member and the smaller-diameter member are brought into contact with a valve seat of a larger diameter and with a valve seat of a smaller diameter provided in the larger-diameter member, respectively. One of the closure members, which corresponds to the check member, is provided with a first pushing portion and a second pushing portion. The first pushing portion faces the smaller-diameter member with a first contact gap interposed therebetween. The second pushing portion opposes to the larger-diameter member with a second gap interposed therebetween. The first contact gap has a dimension set to a value smaller than that of a dimension of the second contact gap. The two closure members are brought into butting contact with each other, thereby primarily enabling the first push portion to separate the smaller-diameter member from the smaller-diameter valve seat and then allowing the second push portion to separate the larger-diameter member from the larger-diameter valve seat.
The foregoing invention offers the following advantage.
When connecting the first coupling and the second coupling to each other, the two closure members are brought into butting contact with one another. Then, primarily, the first push portion separates the smaller-diameter member from the smaller-diameter valve seat, against a small valve-closing force which acts on the smaller-diameter member having a smaller pressure receiving area. Thus a check valve chamber of at least one of the first coupling and the second coupling is deprived of its pressure. This decreases a valve-closing pressure which acts on the larger-diameter member and therefore also reduces a pushing force required when the second push portion separates the larger-diameter member from the larger-diameter valve seat, with the result of reducing the operational force for butting the two closure members against each other.
The present invention still further includes the following quick coupler.
The smaller-diameter valve seat is provided within the larger-diameter member and the smaller-diameter member is inserted thereinto. There is provided a resilient member for urging the smaller-diameter member to the smaller-diameter valve seat. The resilient member exerts an urging force which brings the larger-diameter member into contact with the larger-diameter valve seat through the smaller-diameter member. In this case, the check valve is made compact to result in forming the quick coupler into a structure of small size.